QLocaleXML: Improve documentation, tidy up a bit

Omit parentheses round what python will form into a tuple anyway.
Include trailing commas on last entries of tuples so adding future
entries don't drag the existing line into their diffs.
Let the writer's tag-opener handle attributes, if supplied.
Clean up spacing in some doc-strings.
This is all preparation for further changes, to limit their diffs.

Change-Id: I989ae28bbd235b2af9c1d72467d4741c4f1f20ae
Reviewed-by: Mate Barany <mate.barany@qt.io>

util/locale_database/qlocalexml.py

@@ -110,7 +110,7 @@ class QLocaleXmlReader (object):
     def msLandIanas(self):
         kid = self.__firstChildText
         for elt in self.__eachEltInGroup(self.root, 'windowsZone', 'msLandZones'):
-            yield (kid(elt, 'msid'), kid(elt, 'territorycode'), kid(elt, 'ianaids'))
+            yield kid(elt, 'msid'), kid(elt, 'territorycode'), kid(elt, 'ianaids')
 
     def languageIndices(self, locales):
         index = 0
@@ -260,8 +260,7 @@ class Spacer (object):
         call to self(text) in which text starts with a tag and doesn't
         include its end-tag; indentation decreases if text starts with
         an end-tag. The text is not parsed any more carefully than
-        just described.
-        """
+        just described."""
         if indent is None:
             self.__call = lambda x: x
         else:
@@ -287,6 +286,10 @@ class Spacer (object):
         return self.__call(line)
 
 class QLocaleXmlWriter (object):
+    """Save the full set of locale data to a QLocaleXML file.
+
+    The output saved by this should conform to qlocalexml.rnc's
+    schema."""
     def __init__(self, save = None, space = Spacer(4)):
         """Set up to write digested CLDR data as QLocale XML.
 
@@ -442,7 +445,10 @@ class QLocaleXmlWriter (object):
         self.__scripts.discard(locale.script_code)
         self.__territories.discard(locale.territory_code)
 
-    def __openTag(self, tag):
+    def __openTag(self, tag, **attrs):
+        if attrs:
+            text = ', '.join(f'{k}="{v}"' for k, v in attrs.items())
+            tag = f'{tag} {text}'
         self.__write(f'<{tag}>')
     def __closeTag(self, tag):
         self.__write(f'</{tag}>')
@@ -489,7 +495,8 @@ class Locale (object):
                "longTimeFormat", "shortTimeFormat",
                'byte_unit', 'byte_si_quantified', 'byte_iec_quantified',
                "currencyIsoCode", "currencySymbol", "currencyDisplayName",
-               "currencyFormat", "currencyNegativeFormat")
+               "currencyFormat", "currencyNegativeFormat",
+               )
 
     # Day-of-Week numbering used by Qt:
     __qDoW = {"mon": 1, "tue": 2, "wed": 3, "thu": 4, "fri": 5, "sat": 6, "sun": 7}
@@ -498,12 +505,15 @@ class Locale (object):
     def fromXmlData(cls, lookup, calendars=('gregorian',)):
         """Constructor from the contents of XML elements.
 
-        Single parameter, lookup, is called with the names of XML
-        elements that should contain the relevant data, within a CLDR
-        locale element (within a localeList element); these names are
-        used for the attributes of the object constructed.  Attribute
-        values are obtained by suitably digesting the returned element
-        texts.\n"""
+        First parameter, lookup, is called with the names of XML elements that
+        should contain the relevant data, within a QLocaleXML locale element
+        (within a localeList element); these names mostly match the attributes
+        of the object constructed. Its return must be the full text of the
+        first child DOM node element with the given name. Attribute values are
+        obtained by suitably digesting the returned element texts.
+
+        Optional second parameter, calendars, is a sequence of calendars for
+        which data is to be retrieved."""
         data = {}
         for k in cls.__asint:
             data[k] = int(lookup(k))
@@ -554,7 +564,7 @@ class Locale (object):
                     'longDateFormat', 'shortDateFormat',
                     'longTimeFormat', 'shortTimeFormat',
                     'currencyIsoCode', 'currencySymbol', 'currencyDisplayName',
-                    'currencyFormat', 'currencyNegativeFormat'
+                    'currencyFormat', 'currencyNegativeFormat',
                     ) + tuple(self.propsMonthDay('days')) + tuple(
                 '_'.join((k, cal))
                 for k in self.propsMonthDay('months')